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<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        Array.prototype.myEvery = function ( fn ) {
            var flag ; 
            for( var i = 0 ; i < this.length ; i ++ ) {
                var res = fn( this[i] , i , this ) ; 
                if ( !res ) {
                    flag = false ;
                    break ; 
                } else {
                    flag = true ;
                }
            } 
            return flag ;
        }
        var arr = [ true , true ,  true , true , true , true , true , true ] ;
        var res = arr.myEvery(function( item , key , arr ){
            return item ; 
        });
        console.log(res);
    </script>
</body>
</html>